#include <iostream>
using namespace std;
class Tree{
//你的代码将被嵌在这里
private:
    int ages;
public:
    void setages(int k)
    {
        ages = k;
    }
    void grow(int year)
    {
        ages+=year;
    }
    void age()
    {
        printf("%d\n",ages);
    }
};
int main()
{
    Tree t;
    t.setages(3);
    t.age();
    t.grow(20);
    t.age();
    return 0;
}